In motor compressors for household refrigerators, a very important factor--besides the efficiency--is the noise, i.e. the noise produced by the motor compressor. Since said refrigeration appliances operate also by night, in absence of any sound, it is evident that noise is a very important element in faultless working of a motor compressor. As the sources of noise inside the motor compressor are different, a number of actions for reducing it have been taken e.g. on the casing, on the compressor block and on the mufflers, which are located on the suction and discharge lines; also the friction between the various moving parts has been reduced.
Generally, the structure of suction mufflers is such as to have a narrow passage through which the refrigerant gas flows from a first chamber, where the gas expands, a second chamber, connected to the first one by means of an opening or of a tube and a conduit connecting said second chamber to a suction chamber provided in the cylinder head, which closes the cylinder provided in the compressor block. This traditional muffler system reduces the noise during the suction stroke, but the results are not very satisfactory, since the sound pressure level is very high, as the resonance frequencies of the muffler which may coincide with those of the motor compressor, are not sufficiently attenuated or shifted.
The object of the present invention is to overcome the above described disadvantages.